Calorie Deficit Calculator
Find your TDEE and choose the right calorie deficit for sustainable fat loss — with weekly loss projections, time-to-goal estimates, and protein targets to preserve muscle.
Choosing Your Deficit Size
| Deficit | Weekly Loss | Best For | Muscle Risk |
|---|---|---|---|
| Mild (10%) | ~0.25 kg/week | Small amounts to lose, active individuals | Very low |
| Moderate (20%) | ~0.5 kg/week | Most people — best balance of speed and sustainability | Low (with high protein) |
| Aggressive (25%) | ~0.75 kg/week | Significant weight to lose, short-term phase | Moderate — high protein essential |
Frequently Asked Questions
How big should my calorie deficit be?
A moderate deficit of 500 kcal/day (approximately 20% below TDEE for most people) is the most evidence-backed approach — it produces roughly 0.5 kg (1 lb) of fat loss per week while preserving muscle mass. Larger deficits (25%+) increase muscle loss, cause greater metabolic adaptation, and are harder to sustain. Smaller deficits (10%) are easier to sustain but progress is slower.
How many calories do I need to burn 1 kg of fat?
1 kg of pure body fat contains approximately 7,700 kcal. To lose 1 kg of fat per week, you need a deficit of 1,100 kcal/day — which is aggressive for most people and risks muscle loss. A sustainable rate is 0.5 kg/week (500 kcal/day deficit) or 0.25 kg/week (250 kcal/day deficit). Total body weight loss may differ from fat loss due to water and glycogen changes.
Should I eat back calories burned from exercise?
Partially. This calculator already includes your activity level in the TDEE calculation, so your exercise calories are factored in. If you add extra unplanned exercise sessions, eating back 50–75% of those calories is a reasonable approach — full replacement often leads to over-eating, as calorie burn estimates from exercise are notoriously inaccurate.
How much protein should I eat in a deficit?
Protein requirements increase in a calorie deficit to preserve muscle mass. Aim for 1.6–2.2 g of protein per kg of body weight — at the higher end of this range during aggressive deficits. This calculator shows both a minimum (1.2 g/kg) and recommended (1.6 g/kg) protein target. Higher protein also increases satiety, making deficit eating more manageable.
Why am I not losing weight even in a calorie deficit?
Several factors can cause a stall: (1) Underestimated calorie intake — food tracking errors are common and typically run 20–40% below actual intake; (2) Metabolic adaptation — TDEE decreases as body weight drops; (3) Water retention masking fat loss — especially around resistance training or hormonal cycles; (4) Overestimated activity level — a desk-job person doing 3 gym sessions/week is moderately active at best. Re-measure and re-calculate after each 5 kg of weight lost.